Systems and methods for grounding power line sections to clear faults

ABSTRACT

A system for clearing power transmission line faults includes a sensor network configured to communicate with a transmission line and configured to detect one or more faults on the transmission line, a crowbar configured to coordinately switch first and second ends of a section of the transmission line to respective termination points, wherein the crowbar includes first and second grounding switches disposed respectively at about the first and second ends of the section of the transmission line, and a controller configured to receive information from the sensor network and configured to control the switching of the crowbar in response to the information.

CROSS-REFERENCE TO RELATED PATENT APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.14/921,805, filed Oct. 23, 2015, which is a continuation of U.S.application Ser. No. 14/522,362, filed Oct. 23, 2014, which is acontinuation of U.S. application Ser. No. 13/967,532, filed Aug. 15,2013, now U.S. Pat. No. 8,879,219, which is a continuation of U.S.application Ser. No. 13/609,849, filed Sep. 11, 2012, now U.S. Pat. No.8,537,511, which is a continuation of U.S. application Ser. No.12/460,456, filed Jul. 17, 2009, now U.S. Pat. No. 8,289,665, all ofwhich are incorporated herein by reference in their entireties.

BACKGROUND

Power utilities generate electrical power at remote plants and deliverelectricity to residential, business or industrial customers viatransmission networks and distribution grids. The power utilities maytransmit large quantities of electric power over long distancetransmission networks from power generating plants to regionalsubstations, which then supply the power to local customers using thedistribution grids.

The transmission networks and/or distribution grids may include overheadpower transmission lines suspended by towers or poles. The transmissionlines may, for example, be bare wire conductors made of aluminum.Instead of aluminum, copper wires may be used in medium-voltagedistribution and low-voltage connections to customer premises.

Power loss in transmission lines (in particular, in long distancetransmission lines) is a significant component of the cost ofelectricity. This power loss is a decreasing function of transmissionvoltage. Therefore, power is typically first transmitted as high voltagetransmissions from the remote power plants to geographically diversesubstations. The most common transmission voltages in use are 765, 500,400, 220 kV, etc. Transmission voltages higher than 800 kV are also inuse. From the substations, the received power is sent using cables or“feeders” to local transformers that further reduce the voltage.Voltages below 69 kV are termed subtransmission or distributionvoltages. The outputs of the transformers are connected to a local lowvoltage power distribution grid that can be tapped directly by thecustomers.

Any electric power transmission and distribution system (“deliverysystem”), which includes different complex interacting elements, inoperation is susceptible to disturbances, surges and faults. The faultsmay, for example, include open circuit faults, short circuit faults,earth leakage faults and insulation breakdown. The faults may beproduced as a result of, for example, lightning strikes, mechanicalloading by ice and/or wind, operation of certain electrical equipment,electromagnetic surges, static electricity, and/or induced voltages. Afault often results in overvoltage transients, travelling wave pulsesand uncontrolled release of energy (e.g., arcing), which can causefurther damage to the system and attached loads. Accordingly, electricpower delivery systems are often provided with surge protectors/shunts(e.g., a crowbar circuit) to divert energy to ground or neutral.Further, the electric power delivery equipment may be then de-energizedto allow for fault clearing, recovery or repair.

The surge protectors may include circuitry that is responsive to a rateof change of a current or voltage to prevent a rise above apredetermined value of the current or voltage. In power transmissionsystems, surge protector circuits may allow the voltage on atransmission line conductor to rise very rapidly when a lightning strikeor other surge occurs on the line, until the breakdown voltage of thegas tube, triac, or other crowbar device goes conductive, and theimpedance from the conductor to ground or to some other referencepotential reduces very rapidly.

The term “switchgear” is commonly used, in the context of electric powerdelivery systems, to refer to the combination of electrical disconnects,fuses, relays, and/or circuit breakers used to isolate electricalequipment. Switchgear is used both to de-energize equipment to allowwork to be done and to clear faults downstream.

Consideration is now being given to solutions for interrupting faultcurrents and de-energizing equipment in high voltage electrical powerdelivery systems.

SUMMARY

Approaches for clearing faults in an AC power line are provided.

In an exemplary approach, the effects of a ground-fault on a section ofa transmission line are reduced by crowbaring the section to ground attwo different ends on either side of the fault. The crowbaring actionmay be expected to raise local ground voltage to that of the line,eliminating voltage-drop (e.g., arc) across the fault. The crowbaringaction may be reversed afterwards (e.g., one to a few power cycleslater) at voltage zero-crossings to clear the fault. The electricaland/or physical continuity of the power line may be preserved throughthe crowbaring and reversal actions. The crowbaring action may beconducted in response to an actual line fault, impending line faultand/or a predicted line fault.

An exemplary system for clearing power line faults includes a crowbararranged to switchably ground first and second ends of a section of alive power line using fast acting grounding switches. The crowbar may bearranged to switchably ground the first and second ends of a section ofa live power line without breaking or open circuiting either the firstor the second end of the section of the live power line and preservingthe electrical and/or physical continuity of the live power line. Thecrowbar is arranged to switchably ground the first and second ends ofthe section of the live power line on a power cycle or sub-cycle timescale. The crowbar may be arranged to switchably ground the first andsecond ends of the section of the live power line synchronously and/orsubstantially simultaneously. The crowbar may be further arranged toun-ground the grounded first and second ends of the section of the livepower line after a suitable time interval to clear the fault and restorepower line operations.

The system may include circuits/sensors/processors configured to detectand locate an actual line fault, impending line fault and/or a predictedline fault. The circuits/sensors/processors may be configured to measurepower line events and characteristics including power line voltagesand/or currents, proximate electromagnetic fields, leakage currentsacross an insulator, etc.

BRIEF DESCRIPTION OF THE DRAWINGS

In the accompanying drawings: FIG. 1 is a schematic illustration of anexemplary electrical power delivery system.

FIG. 2 is a schematic illustration of a scheme to isolate and ground afaulted section of transmission power line;

FIG. 3 is a schematic illustration of a scheme to ground a faultedsection of transmission power line while maintaining electrical andphysical continuity of the line, in accordance with the principles ofthe solutions described herein;

FIG. 4 is a block diagram illustrating a system for grounding a faultedsection of transmission power line while maintaining electrical andphysical continuity of the line, in accordance with the principles ofthe solutions described herein; and

FIG. 5 is a flow diagram illustrating an exemplary method for groundinga faulted section of transmission power line while maintainingelectrical and physical continuity of the line, in accordance with theprinciples of the solutions described herein.

Throughout the figures, unless otherwise stated, the same referencenumerals and characters are used to denote like features, elements,components, or portions of the illustrated embodiments.

DETAILED DESCRIPTION

Systems and methods for clearing faults on A.C. power lines in anelectrical power delivery system are provided.

In the following description of exemplary embodiments, reference is madeto the accompanying drawings, which form a part hereof. It will beunderstood that embodiments described herein are exemplary, but are notmeant to be limiting. Further, it will be appreciated that the solutionsdescribed herein can be practiced or implemented by other than thedescribed embodiments. Modified embodiments or alternate embodiments maybe utilized, in the spirit and scope of the solutions described herein.

FIG. 1 shows a simplified representation of an electrical powertransmission and distribution system (e.g., electrical power deliverysystem 100). In system 100, electricity is generated at a power plant(e.g. by generator A) is stepped up in voltage and sent out on highvoltage transmission lines 110 to substation 120. At substation 120,step-down transformers adjust the electrical voltage so it can be routedover main distribution lines 130 to large subdivisions and largecommercial customers. Overhead (140 a) or underground (140 b) localdistribution lines are fed from main distribution lines 130 to deliverpower to smaller neighborhoods and businesses. Similarly, overhead (150a) or underground (150 b) service lines then deliver power to individualcustomer locations. System 100 may, for example, deliver multiple-phasepower.

It will be understood that in practice, system 100 may include manysubstations 120 and that high voltage transmission lines 110 may extendover several hundreds of miles supported by a large number oftransmission towers 160. System 100 may also include diagnosticequipment (e.g., for fault detection or monitoring) and protectiveswitchgear (e.g., circuit breakers, reclosers and switchers, relays,surge protectors, lightning arresters, etc.) placed throughout thesystem (e.g., at towers, substations, generators, transformers, etc.).

System 100 may, for example, include circuit breakers and automatedgrounding devices disposed at suitable intervals along transmissionlines 110, which are arranged to interrupt line current and to groundconductors at suitable points.

FIG. 2 shows a schematic arrangement of switch gear (e.g., circuitbreakers 210 and grounding devices or switches 220) for transmissionlines 110 (a, b and c) that carry three phase power from an electricitygenerator to a user.

Circuit breakers 210 may be of a type that can open and close on faultcurrents. A suitable circuit breaker 210 may be an open air isolatorswitch or a switch insulated by some other substance (e.g., oil, vacuum,gas, pressurized gas such as sulfur hexafluoride gas (SF6)). Suitablecircuit breakers 210 may be rated by their ability to interrupt faultcurrents, which may surge to many hundreds or thousands of amps, and toquench the arc that may develop when circuit breaker contacts open. Atypical circuit breaker may be able to terminate all current flow veryquickly (e.g., between 30 ms and 150 ms) and automatically attempt toreclose.

Most frequent faults on high voltage overhead lines aresingle-phase-to-ground faults. Accordingly, circuit breakers 210 may bearranged to allow a single pole of a three-phase line to trip, insteadof tripping all three poles. For some classes of faults this may improvesystem stability and availability. Further, most faults are transient;for example, lightning induced faults (e.g., fault at location A, FIG.2). Automated reclosers (not shown) may attempt to reclose circuitbreakers 210 automatically in order to clear the fault. After the presetnumber of attempted reclosings, circuit breaker 210 may lock out leavingthe faulted section of line 110 a isolated for manual intervention forfault clearing.

After ground fault A is first isolated by circuit breaker 210's singlepole switching in response to a fault, the initial fault current(primary arc) on line 110 a changes its state to an intermittent,unstable current with lower amplitude (secondary arc). The secondary arcmay be supplied energy by the healthy phase lines (e.g., 110 b and c)through inductive and capacitive coupling. The secondary arc mayextinguish within the dead time of the single pole reclosing. However,the secondary arc can have a long duration, which endangers successfulreclosing of circuit breaker 210.

To overcome the effects of secondary arcs, system 200 may includegrounding switches 220 that are arranged to ground faulted line 110 a inorder to sink secondary arc currents. Grounding switches 220 may groundline 110 a only temporarily, for example, between the opening andreclosing of circuit breaker 210, to sink secondary arc currents toclear faults, and thereby encourage successful reclosing of circuitbreaker 210. For this purpose, grounding switches 220 may be fast actingor high speed gas insulated switch gear devices, for example, of thetype described in Kenji Annou et al. U.S. Pat. No. 5,638,524 andWatanabe et al. U.S. Pat. No. 5,543,597, both of which are incorporatedby reference in their entireties herein.

Further, approaches herein for clearing faults in electrical powerdelivery systems involve schemes for automatically grounding an entirelength or section of a power transmission line in response to a fault oranticipated fault in or on the section. In one such approach shown inFIG. 3, a fault or anticipated fault A on a power transmission line 110a may be segregated or isolated by temporarily crowbaring a section 110a′ of line 110 a to respective grounds (e.g., 318 and 318′) orrespective termination points (e.g., 314 and 314′) at two differentsites on either side of the fault or anticipated fault.

A crowbar arrangement 310 including a suitably located pair of groundingswitches 312 may be used for the grounding, terminating or crowbaringaction. Adjoining sections of line 110 a that are upstream anddownstream of faulted section 110 a′ may remain in electrical continuityas the grounding or crowbaring action need not involve circuit breakingactions. However, the grounding, terminating or crowbaring action may beexpected to raise local ground voltage to that of faulted section 110a′, and consequently eliminate or reduce any voltage drop and arcingacross fault A. The grounding, terminating, or crowbaring action may bereversed soon afterwards, for example, in the expectation that fault Ahas cleared. The reversal of grounding or crowbaring action may beimplemented by reopening grounding switches 312 one or a few powercycles after the switches are closed. The reopening of groundingswitches 312/crowbar 310 may be set to occur at or about voltagezero-crossings on line 110 a.

With reference to FIG. 3, it will be understood that respective grounds(318 and 318′) may correspond to different ground potential values atthe two different sites. Further, the potentials at respectivetermination points (314 and 314′) may be adjustable relative to localground potential by optional termination elements (e.g., 316 and 316′,respectively) disposed between the termination points and the grounds atthe two different sites on either side of the fault. One or both oftermination elements 316 and 316′ may, for example, be configured toprovide user-adjustable termination point potentials. Use of suchtermination elements (e.g., user-adjustable capacitances or EMF sources)may allow control of the potential difference across a crowbarred orterminated line section and/or control over the direction of charge flowout of the grounded or terminated line section (e.g., faulted oranticipated fault section 110 a′).

FIG. 4 shows exemplary components of a system 400 for crowbaring faultedsections of a power transmission line in a power delivery network (e.g.,system 100). System 400 includes a plurality of grounding switches 420,which may be coupled to fault sensing network 410. System 400 also mayinclude a controller 430 configured to coordinate operation of theplurality of grounding switches 420 to, for example, synchronously orsubstantially simultaneously, ground or terminate both ends of a faultedsection of the power transmission line.

Fault sensing network 410 includes one or more sensors (e.g., ammeters,voltammeters, magnetometers, optical sensors, lightning detectors,insulator flashover detectors, digital protective relays, etc.) arrangedto detect and/or locate faults or possible faults on power transmissionlines. Exemplary fault detection and location system for powertransmission and distribution lines and locating are described, forexample, in Kejeriwal et al. U.S. Pat. No. 5,343,155, and Elkateb et al.U.S. Pat. No. 4,390,835, Bjorklun et al. U.S. Pat. No. 5,903,155, andBorchert, et al. U.S. Pat. No. 6,822,457, all of which are incorporatedby reference herein in their entireties. Fault sensing network 410 maybe a part of a larger network monitoring arrangement that monitors theenvironment, behavior, status, quality, and/or performance of a powertransmission network and its components (e.g., transformers, lines,towers, insulators, switch gear, weather conditions, lightning strikes,loading, etc.). Fault sensing network 410 may be configured to identifya fault by detecting a fault current. Further, fault sensing network 410may be configured to detect an impending fault by measuring, forexample, fault precursors (e.g., rising voltages, rising fields, leakagecurrents across insulator, impending lightning strikes etc.). Faultsensing network 410 also may include processors and algorithms forpredicting fault occurrence (in time and space) based, for example, ontemporal line events (e.g., loading, switching, current and voltagevalues, environmental and/or weather events etc.) and linecharacteristics (e.g., line/insulator physical and mechanicalproperties, environment and/or weather conditions, etc.).

Fault sensing network 410 may provide signals and data directly togrounding switches 420 or via other suitable mechanical, optical and/orelectrical interfaces (e.g., via optional controller 430).

Grounding switches 420 may include suitable line grounding switches(e.g., grounding devices 220, 312) disposed at suitable locations andspacing throughout power delivery network. The line grounding switchesmay, for example, include a mechanical switch, an electro-mechanicalswitch, a solid state switch, an SCR, an IGBT, a thyristor, anoptoelectronic switch, an Austin switch, a photo-activated switch, acrossed-field switch, a gas-based switch, and/or a vacuum-based switch.The line grounding switches may be fast acting switches that are capableof switching actions, for example, on a power cycle or sub-cycle timescales.

In an implementation of system 400, the line grounding switches may bedisposed, for example, at nodes in the network or at any suitableintranodal distances for sectionalizing a power line in workable orpractical segments or lengths. The line grounding switches may, forexample, be disposed at or proximate to a set of transmission linetowers in the power delivery network so that the power line can besectionalized in a discrete lengths corresponding to one or moreinter-tower distances. The plurality of grounding switches may beconfigured so that an appropriate pair of grounding switches 420responds to a detected or anticipated fault in a section of the powerline (e.g., 110 a′) by automatically closing and grounding both ends ofthe section. The pair of grounding switches 420 may be configured tosynchronously or substantially simultaneously close and ground both endsof the section. Grounding or terminating both ends of the section may beexpected to raise a local ground voltage to substantially that of thesection of the live power line. This action may reduce or eliminatevoltage drop and arcing across a fault in the section.

The grounding switches 420 may be further configured to reopen andun-ground the faulted section after a suitable time interval to clearthe fault. Grounding switches 420 may be configured to maintain theelectrical and/or physical continuity of line (e.g., 110 a) during theclosing and reopening operations.

Optional controller/processor 430 may be configured to coordinate theoperation of grounding switches 420 in response to fault sensing network410 signals and/or data. Optional controller/processor 430 may includeany suitable arrangement of electromagnetic, electrical, magnetic,optical and other types of devices or elements (e.g., relays, interfacecircuits, network connections, data and signal processing units,address/data bus, memory devices, microprocessor, microcontroller,digital signal processor, specialized mathematical processor, and/or anyother type of computing device, etc.). It will be understood that thevarious system 400 components (fault sensing network 410, groundingswitches 420 and controller 430) may be physically coupled andintegrated so that parts of a component may be shared with othercomponents and or disposed in common units. For example, fault sensingnetwork 410 and grounding switches 420 may share or use common linecurrent sensing devices.

Further, all components of system 400 may be coupled to or integratedwith common control systems deployed for managing electrical powertransmission networks (e.g., Supervisory Control And Data Acquisition(SCADA) systems).

FIG. 5 is a flow diagram showing exemplary steps in a method 500 forclearing faults in a power transmission network. Method 500 includesdetecting, anticipating or predicting a power line fault and itslocation (510), and then grounding both ends of a “faulted” section ofthe line containing the fault or putative fault (520) while preservingpower line continuity. Method 500 further includes reversing thegrounding of the faulted section to restore power line operation forfault clearance (530).

In the following detailed description, reference is made to theaccompanying drawings, which form a part hereof. In the drawings,similar symbols typically identify similar components, unless contextdictates otherwise. The illustrative embodiments described in thesummary, detailed description, drawings, and claims are not meant to belimiting. Other embodiments may be utilized, and other changes may bemade, without departing from the spirit or scope of the subject matterpresented here. Those having skill in the art will recognize that thestate of the art has progressed to the point where there is littledistinction left between hardware and software implementations ofaspects of systems; the use of hardware or software is generally (butnot always, in that in certain contexts the choice between hardware andsoftware can become significant) a design choice representing cost vs.efficiency tradeoffs. Those having skill in the art will appreciate thatthere are various vehicles by which processes and/or systems and/orother technologies described herein can be effected (e.g., hardware,software, and/or firmware), and that the preferred vehicle will varywith the context in which the processes and/or systems and/or othertechnologies are deployed. For example, if an implementer determinesthat speed and accuracy are paramount, the implementer may opt for amainly hardware and/or firmware vehicle; alternatively, if flexibilityis paramount, the implementer may opt for a mainly softwareimplementation; or, yet again alternatively, the implementer may opt forsome combination of hardware, software, and/or firmware. Hence, thereare several possible vehicles by which the processes and/or devicesand/or other technologies described herein may be effected, none ofwhich is inherently superior to the other in that any vehicle to beutilized is a choice dependent upon the context in which the vehiclewill be deployed and the specific concerns (e.g., speed, flexibility, orpredictability) of the implementer, any of which may vary. Those skilledin the art will recognize that optical aspects of implementations willtypically employ optically-oriented hardware, software, and or firmware.

The foregoing detailed description has set forth various embodiments ofthe devices and/or processes via the use of block diagrams, flowcharts,and/or examples. Insofar as such block diagrams, flowcharts, and/orexamples contain one or more functions and/or operations, it will beunderstood by those within the art that each function and/or operationwithin such block diagrams, flowcharts, or examples can be implemented,individually and/or collectively, by a wide range of hardware, software,firmware, or virtually any combination thereof. In one embodiment,several portions of the subject matter described herein may beimplemented via Application Specific Integrated Circuits (ASICs), FieldProgrammable Gate Arrays (FPGAs), digital signal processors (DSPs), orother integrated formats. However, those skilled in the art willrecognize that some aspects of the embodiments disclosed herein, inwhole or in part, can be equivalently implemented in integratedcircuits, as one or more computer programs running on one or morecomputers (e.g., as one or more programs running on one or more computersystems), as one or more programs running on one or more processors(e.g., as one or more programs running on one or more microprocessors),as firmware, or as virtually any combination thereof, and that designingthe circuitry and/or writing the code for the software and or firmwarewould be well within the skill of one of skill in the art in light ofthis disclosure. In addition, those skilled in the art will appreciatethat the mechanisms of the subject matter described herein are capableof being distributed as a program product in a variety of forms, andthat an illustrative embodiment of the subject matter described hereinapplies regardless of the particular type of signal bearing medium usedto actually carry out the distribution. Examples of a signal bearingmedium include, but are not limited to, the following: a recordable typemedium such as a floppy disk, a hard disk drive, a Compact Disc (CD), aDigital Video Disk (DVD), a digital tape, a computer memory, etc.; and atransmission type medium such as a digital and/or an analogcommunication medium (e.g., a fiber optic cable, a waveguide, a wiredcommunications link, a wireless communication link, etc.). Further,those skilled in the art will recognize that the mechanical structuresdisclosed are exemplary structures and many other forms and materialsmay be employed in constructing such structures.

In a general sense, those skilled in the art will recognize that thevarious embodiments described herein can be implemented, individuallyand/or collectively, by various types of electro-mechanical systemshaving a wide range of electrical components such as hardware, software,firmware, or virtually any combination thereof; and a wide range ofcomponents that may impart mechanical force or motion such as rigidbodies, spring or torsional bodies, hydraulics, and electro-magneticallyactuated devices, or virtually any combination thereof. Consequently, asused herein “electro-mechanical system” includes, but is not limited to,electrical circuitry operably coupled with a transducer (e.g., anactuator, a motor, a piezoelectric crystal, etc.), electrical circuitryhaving at least one discrete electrical circuit, electrical circuitryhaving at least one integrated circuit, electrical circuitry having atleast one application specific integrated circuit, electrical circuitryforming a general purpose computing device configured by a computerprogram (e.g., a general purpose computer configured by a computerprogram which at least partially carries out processes and/or devicesdescribed herein, or a microprocessor configured by a computer programwhich at least partially carries out processes and/or devices describedherein), electrical circuitry forming a memory device (e.g., forms ofrandom access memory), electrical circuitry forming a communicationsdevice (e.g., a modem, communications switch, or optical-electricalequipment), and any non-electrical analog thereto, such as optical orother analogs. Those skilled in the art will also appreciate thatexamples of electro-mechanical systems include but are not limited to avariety of consumer electronics systems, as well as other systems suchas motorized transport systems, factory automation systems, securitysystems, and communication/computing systems. Those skilled in the artwill recognize that electro-mechanical as used herein is not necessarilylimited to a system that has both electrical and mechanical actuationexcept as context may dictate otherwise.

In a general sense, those skilled in the art will recognize that thevarious aspects described herein which can be implemented, individuallyand/or collectively, by a wide range of hardware, software, firmware, orany combination thereof can be viewed as being composed of various typesof “electrical circuitry.” Consequently, as used herein “electricalcircuitry” includes, but is not limited to, electrical circuitry havingat least one discrete electrical circuit, electrical circuitry having atleast one integrated circuit, electrical circuitry having at least oneapplication specific integrated circuit, electrical circuitry forming ageneral purpose computing device configured by a computer program (e.g.,a general purpose computer configured by a computer program which atleast partially carries out processes and/or devices described herein,or a microprocessor configured by a computer program which at leastpartially carries out processes and/or devices described herein),electrical circuitry forming a memory device (e.g., forms of randomaccess memory), and/or electrical circuitry forming a communicationsdevice (e.g., a modem, communications switch, or optical-electricalequipment). Those having skill in the art will recognize that thesubject matter described herein may be implemented in an analog ordigital fashion or some combination thereof.

Those skilled in the art will recognize that it is common within the artto implement devices and/or processes and/or systems in the fashion(s)set forth herein, and thereafter use engineering and/or businesspractices to integrate such implemented devices and/or processes and/orsystems into more comprehensive devices and/or processes and/or systems.That is, at least a portion of the devices and/or processes and/orsystems described herein can be integrated into other devices and/orprocesses and/or systems via a reasonable amount of experimentation.Those having skill in the art will recognize that examples of such otherdevices and/or processes and/or systems might include—as appropriate tocontext and application—all or part of devices and/or processes and/orsystems for generation, transmission and distribution of electricalpower, a communications system (e.g., a networked system, a telephonesystem, a Voice over IP system, wired/wireless services, etc.).

One skilled in the art will recognize that the herein describedcomponents (e.g., steps), devices, and objects and the discussionaccompanying them are used as examples for the sake of conceptualclarity and that various configuration modifications are within theskill of those in the art. Consequently, as used herein, the specificexemplars set forth and the accompanying discussion are intended to berepresentative of their more general classes. In general, use of anyspecific exemplar herein is also intended to be representative of itsclass, and the non-inclusion of such specific components (e.g., steps),devices, and objects herein should not be taken as indicating thatlimitation is desired.

With respect to the use of substantially any plural and/or singularterms herein, those having skill in the art can translate from theplural to the singular and/or from the singular to the plural as isappropriate to the context and/or application. The varioussingular/plural permutations are not expressly set forth herein for sakeof clarity.

The herein described subject matter sometimes illustrates differentcomponents contained within, or connected with, different othercomponents. It is to be understood that such depicted architectures aremerely exemplary, and that in fact many other architectures can beimplemented which achieve the same functionality. In a conceptual sense,any arrangement of components to achieve the same functionality iseffectively “associated” such that the desired functionality isachieved. Hence, any two components herein combined to achieve aparticular functionality can be seen as “associated with” each othersuch that the desired functionality is achieved, irrespective ofarchitectures or intermedial components. Likewise, any two components soassociated can also be viewed as being “operably connected”, or“operably coupled”, to each other to achieve the desired functionality,and any two components capable of being so associated can also be viewedas being “operably couplable”, to each other to achieve the desiredfunctionality. Specific examples of operably couplable include but arenot limited to physically mateable and/or physically interactingcomponents and/or wirelessly interactable and/or wirelessly interactingcomponents and/or logically interacting and/or logically interactablecomponents.

While particular aspects of the present subject matter described hereinhave been shown and described, it will be apparent to those skilled inthe art that, based upon the teachings herein, changes and modificationsmay be made without departing from the subject matter described hereinand its broader aspects and, therefore, the appended claims are toencompass within their scope all such changes and modifications as arewithin the true spirit and scope of the subject matter described herein.Furthermore, it is to be understood that the invention is defined by theappended claims. It will be understood by those within the art that, ingeneral, terms used herein, and especially in the appended claims (e.g.,bodies of the appended claims) are generally intended as “open” terms(e.g., the term “including” should be interpreted as “including but notlimited to,” the term “having” should be interpreted as “having atleast,” the term “includes” should be interpreted as “includes but isnot limited to,” etc.). It will be further understood by those withinthe art that if a specific number of an introduced claim recitation isintended, such an intent will be explicitly recited in the claim, and inthe absence of such recitation no such intent is present. For example,as an aid to understanding, the following appended claims may containusage of the introductory phrases “at least one” and “one or more” tointroduce claim recitations. However, the use of such phrases should notbe construed to imply that the introduction of a claim recitation by theindefinite articles “a” or “an” limits any particular claim containingsuch introduced claim recitation to inventions containing only one suchrecitation, even when the same claim includes the introductory phrases“one or more” or “at least one” and indefinite articles such as “a” or“an” (e.g., “a” and/or “an” should typically be interpreted to mean “atleast one” or “one or more”); the same holds true for the use ofdefinite articles used to introduce claim recitations. In addition, evenif a specific number of an introduced claim recitation is explicitlyrecited, those skilled in the art will recognize that such recitationshould typically be interpreted to mean at least the recited number(e.g., the bare recitation of “two recitations,” without othermodifiers, typically means at least two recitations, or two or morerecitations). Furthermore, in those instances where a conventionanalogous to “at least one of A, B, and C, etc.” is used, in generalsuch a construction is intended in the sense one having skill in the artwould understand the convention (e.g., “a system having at least one ofA, B, and C” would include but not be limited to systems that have Aalone, B alone, C alone, A and B together, A and C together, B and Ctogether, and/or A, B, and C together, etc.). In those instances where aconvention analogous to “at least one of A, B, or C, etc.” is used, ingeneral such a construction is intended in the sense one having skill inthe art would understand the convention (e.g., “a system having at leastone of A, B, or C” would include but not be limited to systems that haveA alone, B alone, C alone, A and B together, A and C together, B and Ctogether, and/or A, B, and C together, etc.). It will be furtherunderstood by those within the art that virtually any disjunctive wordand/or phrase presenting two or more alternative terms, whether in thedescription, claims, or drawings, should be understood to contemplatethe possibilities of including one of the terms, either of the terms, orboth terms. For example, the phrase “A or B” will be understood toinclude the possibilities of “A” or “B” or “A and B.”

While various aspects and embodiments have been disclosed herein, otheraspects and embodiments will be apparent to those skilled in the art.The various aspects and embodiments disclosed herein are for purposes ofillustration and are not intended to be limiting, with the true scopeand spirit being indicated by the following claims.

What is claimed is:
 1. A system for clearing power transmission linefaults, comprising: a crowbar configured to coordinately switch firstand second ends of a section of a transmission line to respectivetermination points, wherein the crowbar includes first and secondgrounding switches disposed respectively at about the first and secondends of the section of the transmission line, and wherein the crowbar isconfigured to control the switching of the first and second groundingswitches in response to a predicted fault.
 2. The system of claim 1,wherein the crowbar comprises at least one of a mechanical switch, anelectro-mechanical switch, a solid state switch, an SCR, an IGBT, athyristor, an optoelectronic switch, an Austin switch, a photo-activatedswitch, a crossed-field switch, a gas-based switch, and a vacuum-basedswitch.
 3. The system of claim 1, further comprising: a firsttermination element; and a second termination element, wherein the firsttermination element and the second termination element are configured tocontrol a potential difference across the section of the transmissionline.
 4. The system of claim 1, further comprising: a first terminationelement; and a second termination element, wherein the first terminationelement and the second termination element are configured to control thedirection of charge flow out of the section of the transmission line. 5.A system for clearing power transmission line faults, comprising: acontroller programmed to control switching of a first grounding switchand a second grounding switch based on information received by thecontroller indicative of a predicted fault on a transmission line. 6.The system of claim 5, further comprising: a first grounding switchconfigured to be disposed at a first end of the section of thetransmission line; a second grounding switch configured to be disposedat a second end of the section of the transmission line, wherein thefirst ground switch and the second grounding switch are configured tocoordinately switch the first end and the second end of the section ofthe transmission line to respective termination points; a firsttermination element; and a second termination element, wherein the firsttermination element and the second termination element are configured tocontrol a potential difference across the section of the transmissionline or to control the direction of charge flow out of the section ofthe transmission line.
 7. The system of claim 5, wherein the firstgrounding switch and the second grounding switch each comprises at leastone of a mechanical switch, an electro-mechanical switch, a solid stateswitch, an SCR, an IGBT, a thyristor, an optoelectronic switch, anAustin switch, a photo-activated switch, a crossed-field switch, agas-based switch, and a vacuum-based switch.
 8. The system of claim 5,further comprising: a sensor network, wherein the sensor network isconfigured to predict the fault on the transmission line.
 9. The systemof claim 8, wherein the sensor network includes a circuit configured tomeasure transmission line characteristics including voltages, currents,phases and/or frequencies.
 10. The system of claim 9, wherein the sensornetwork includes a circuit configured to measure transmission linecharacteristics including voltages, currents, phases and/or frequencies.11. The system of claim 10, wherein the circuitry is configured topredict a line fault and its location based at least in part on risingline voltages or currents, rising fields, and/or leakage currents acrossan insulator.
 12. A system for clearing power transmission line faults,comprising: a crowbar configured to coordinately switch first and secondends of a section of a transmission line to respective terminationpoints, wherein the crowbar includes first and second grounding switchesdisposed respectively at about the first and second ends of the sectionof the transmission line; and a controller configured to control theswitching of the crowbar based on a predicted fault on the transmissionline.
 13. The system of claim 12, wherein the respective terminationpoints are configured to be at physical ground potentials and/or atfinite potentials relative to the physical ground potentials.
 14. Thesystem of claim 12, wherein at least one termination point is configuredto be separated from physical ground potential by a termination element.15. The system of claim 14, wherein the termination element comprisesone or more capacitances and/or EMF sources.
 16. The system of claim 12,further comprising a sensor network configured to communicate with thetransmission line and configured to predict the fault; wherein thesensor network includes a circuit configured to measure transmissionline characteristics including voltages, currents, phases and/orfrequencies.
 17. The system of claim 12, wherein the sensor networkincludes circuitry configured to detect and locate a line fault.
 18. Thesystem of claim 17, wherein the circuitry is configured to predict aline fault and its location based at least in part on rising linevoltages or currents, rising fields, and/or leakage currents across aninsulator.
 19. The system of claim 12, wherein the crowbar comprises atleast one of a mechanical switch, an electro-mechanical switch, a solidstate switch, an SCR, an IGBT, a thyristor, an optoelectronic switch, anAustin switch, a photo-activated switch, a crossed-field switch, agas-based switch, and a vacuum-based switch.
 20. The system of claim 12,further comprising: a first termination element; and a secondtermination element, wherein the first termination element and thesecond termination element are configured to control a potentialdifference across the section of the transmission line.
 21. The systemof claim 20, wherein the first termination element and the secondtermination element each comprises one or more capacitances and/or EMFsources.
 22. The system of claim 12, further comprising: a firsttermination element; and a second termination element, wherein the firsttermination element and the second termination element are configured tocontrol the direction of charge flow out of the section of thetransmission line.
 23. The system of claim 22, wherein the firsttermination element and the second termination element each comprisesone or more capacitances and/or EMF sources.